tropical cyclones

• Tropical cyclones develop when the sea temperature is 26.5°C or higher
• The source area of most tropical cyclones is between 5°C and 30°C North and south of the equator
• Warm, moist air rises and condenses which releases huge amounts of energy, make storms powerful
• The earth's rotation deflects the path of the winds causing the cyclone to spin
• Cyclones intensify due to energy from warm waters
• Cyclones dissipate when the move over land or cooler waters as the warm water energy supply is cut off
• Climate change may cause source areas of cyclones to change
• The centre of the cyclones called the eye
• The eye of the cyclone has very low pressure ,light winds ,no clouds, no rain and high temperature
• The eye is surrounded by the eye wall
• in the eyewall, there is very strong winds, storm clouds, torrential rain and low temperatures
• Tropical cyclones spin clockwise in the southern hemisphere and anticlockwise in the northern hemisphere
• At the edges of the cyclone, the wind speed falls, the clouds become smaller, the rain is less intense, and temperature rises
• Physical hazards caused by tropical cyclones:

  •high winds

  •Intense rainfall

  •Storm surges

  •Coastal flooding

  •Landslides
• Physical hazards of tropical cyclones' impact on people:

  •Drowning in strong currents by floodwater

  •Windspeeds destroys homes leaving people homeless

  •Debris from high winds can injure or kill people

  •Electricity supplies can be cut off

  •unemployment due to damaged buildings
• Physical hazards by tropical cyclones impact on the environment:

  •Storm surges can erode beaches

  •Landslides deposit sediments in waters that can kill wildlife

  •Flooding can damage industrial buildings on the coast
• Three types of vulnerability for counties susceptible to tropical cyclones:

  •Physical vulnerability

  •Economic vulnerability

  •Social vulnerability
• Physical vulnerability:

  •low-lying coastlines are vulnerable to storm surge flooding

  •Steep hills can increase risk of land slides
• Economic vulnerability:

  •Poorer countries are economically vulnerable as many depend on agriculture which is often badly affected

  •richer countries are economically vulnerable as damaged buildings cost alot of money to replace
• Social vulnerability-poorer countries are more socially vulnerable because:

  •Buildings are poor quality so are easily damaged

  •Health care is not good so there is a struggle to treat casualties

  •Little money for Flood defences or training emergency teams
• Three strategies to prepare and respond to tropical cyclones:

  •forecasting

  •Evaluation

  •defences
• Tropical cyclones are classified by the saffir-simpson scale
• Forecasting: predicting where and when tropical cyclones will hit land
• 3 ways of forecasting:

  •Atmospheric pressure

  •Modelling

  •Satellite tracking
• Atmospheric pressure- buoys are anchored in tropical ocean areas which send Atmospheric pressure readings
• Modelling: when data is put into sophisticated modelling programs, which generate estimates of likely tracks for the cyclone
• Satellite tracking: allows for huge areas of the ocean to be monitored. The process of the cyclone can be monitored in real time
• Forecasting can give people time to evacuate and to protect their homes
• Evacuation: warning strategies alert people to leave the area and find a safe place
• Defences: for example sea walls can be built along the coast to prevent damage from storm surges. This reduces the amount of damage, injury, deaths etc